Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$91.89	4.844%	$96.3412	$96.34	$96.35	$96.30
Purchase #2	$204.41	5.862%	$216.3925	$216.39	$216.40	$216.40
Purchase #3	$100.97	10.857%	$111.9323	$111.93	$111.95	$111.90
Purchase #4	$194.88	8.239%	$210.9362	$210.94	$210.95	$210.90
Purchase #5	$176.47	8.189%	$190.9211	$190.92	$190.90	$190.90
Purchase #6	$210.40	9.477%	$230.3396	$230.34	$230.35	$230.30
Purchase #7	$54.52	12.143%	$61.1404	$61.14	$61.15	$61.10
7 purchase totals =	$1,033.54		$1,118.0033	$1,118.00	$1,118.05	$1,117.80